2,217 research outputs found
Ames ER-2 ozone measurements
The objective of this research is to study ozone (O3) in the stratosphere. Measurements of the ozone mixing ratio at 1 s intervals are obtained with an ultraviolet photometer which flies on the ER-2 aircraft. The photometer determines the amount of ozone in air by measuring the transmission of ultraviolet light through a fixed path with and without ambient O3 present
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Lithium and carbon isotopic fractionations between the alteration assemblages of Nakhla and Lafayette
Nakhla and Lafayette delta 7Li values for samples and extracts (4.1-14.2�) are consistent with brine evaporation. Relatively 13C-poor siderite in Lafayette suggests more than one carbon source was sampled
Book Review: A Review of \u3ci\u3eMexican Law\u3c/i\u3e by Stephen Zamora, Jose Ramon Cossio, Leonel Pereznieto, Jose Roldan-Xopa, and David Lopez
Das Deutsche Rechtswörterbuch: Vorstellung des Wörterbuchs und lexikographische Praxis am Beispiel "magdeburgisch"
SplicerAV: a tool for mining microarray expression data for changes in RNA processing
<p>Abstract</p> <p>Background</p> <p>Over the past two decades more than fifty thousand unique clinical and biological samples have been assayed using the Affymetrix HG-U133 and HG-U95 GeneChip microarray platforms. This substantial repository has been used extensively to characterize changes in gene expression between biological samples, but has not been previously mined <it>en masse </it>for changes in mRNA processing. We explored the possibility of using HG-U133 microarray data to identify changes in alternative mRNA processing in several available archival datasets.</p> <p>Results</p> <p>Data from these and other gene expression microarrays can now be mined for changes in transcript isoform abundance using a program described here, SplicerAV. Using <it>in vivo </it>and <it>in vitro </it>breast cancer microarray datasets, SplicerAV was able to perform both gene and isoform specific expression profiling within the same microarray dataset. Our reanalysis of Affymetrix U133 plus 2.0 data generated by <it>in vitro </it>over-expression of HRAS, E2F3, beta-catenin (CTNNB1), SRC, and MYC identified several hundred oncogene-induced mRNA isoform changes, one of which recognized a previously unknown mechanism of <it>EGFR </it>family activation. Using clinical data, SplicerAV predicted 241 isoform changes between low and high grade breast tumors; with changes enriched among genes coding for guanyl-nucleotide exchange factors, metalloprotease inhibitors, and mRNA processing factors. Isoform changes in 15 genes were associated with aggressive cancer across the three breast cancer datasets.</p> <p>Conclusions</p> <p>Using SplicerAV, we identified several hundred previously uncharacterized isoform changes induced by <it>in vitro </it>oncogene over-expression and revealed a previously unknown mechanism of EGFR activation in human mammary epithelial cells. We analyzed Affymetrix GeneChip data from over 400 human breast tumors in three independent studies, making this the largest clinical dataset analyzed for <it>en masse </it>changes in alternative mRNA processing. The capacity to detect RNA isoform changes in archival microarray data using SplicerAV allowed us to carry out the first analysis of isoform specific mRNA changes directly associated with cancer survival.</p
Quinolone signaling in the cell-to-cell communication system of Pseudomonas aeruginosa
Numerous species of bacteria use an elegant
regulatory mechanism known as quorum sensing to control
the expression of specific genes in a cell-density dependent
manner. In Gram-negative bacteria, quorum sensing systems
function through a cell-to-cell signal molecule (autoinducer)
that consists of a homoserine lactone with a fatty acid side
chain. Such is the case in the opportunistic human pathogen
Pseudomonas aeruginosa, which contains two quorum sensing
systems (las and rhl) that operate via the autoinducers,
N-(3-oxododecanoyl)-L-homoserine lactone and N-butyryl-Lhomoserine
lactone. The study of these signal molecules has
shown that they bind to and activate transcriptional activator
proteins that specifically induce numerous P. aeruginosa
virulence genes. We report here that P. aeruginosa produces
another signal molecule, 2-heptyl-3-hydroxy-4-quinolone,
which has been designated as the Pseudomonas quinolone
signal. It was found that this unique cell-to-cell signal controlled
the expression of lasB, which encodes for the major
virulence factor, LasB elastase. We also show that the synthesis
and bioactivity of Pseudomonas quinolone signal were
mediated by the P. aeruginosa las and rhl quorum sensing
systems, respectively. The demonstration that 2-heptyl-3-
hydroxy-4-quinolone can function as an intercellular signal
sheds light on the role of secondary metabolites and shows
that P. aeruginosa cell-to-cell signaling is not restricted to
acyl-homoserine lactones. Originally published Proc. Natl. Acad. Sci, Vol. 96, No. 20, Sep. 199
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